Yes, I have the stock app notifications disabled. I am getting the same message multiple times in Handcent. I also updated the app and it is still doing it almost every time I get a text message. I did notice the update mentioned Motorola phones so maybe the fix was just for them since it has not helped me.

It is from almost everyone. At first I thought it was just the people I know that use Sprint but now it is from all carriers. Occasionally I will just get the single message but it is almost every time I get the same message 2-3 times.